tlv.hh

// -*- c-basic-offset: 4; tab-width: 8; indent-tabs-mode: t -*-
// vim:set sts=4 ts=8:

// Copyright (c) 2001-2009 XORP, Inc.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License, Version
// 2.1, June 1999 as published by the Free Software Foundation.
// Redistribution and/or modification of this program under the terms of
// any other version of the GNU Lesser General Public License is not
// permitted.
// 
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. For more details,
// see the GNU Lesser General Public License, Version 2.1, a copy of
// which can be found in the XORP LICENSE.lgpl file.
// 
// XORP, Inc, 2953 Bunker Hill Lane, Suite 204, Santa Clara, CA 95054, USA;
// http://xorp.net

// $XORP: xorp/libxorp/tlv.hh,v 1.9 2008/10/02 21:57:36 bms Exp $

#ifndef __LIBXORP_TLV_HH__
#define __LIBXORP_TLV_HH__

class Tlv {
 public:
    Tlv() : _fp(0)
    {}

    bool open(string& fname, bool read) {
    if ("-" == fname) {
        _fp = read ? stdin : stdout;
    } else {
        _fp = fopen(fname.c_str(), read ? "r" : "w");
    }
    if (0 == _fp)
        return false;

    return true;
    }

    bool read(uint32_t& type, vector<uint8_t>& data) {
    uint32_t n;
    if (1 != fread(&n, sizeof(n), 1, _fp))
        return false;
    
    type = ntohl(n);

    if (1 != fread(&n, sizeof(n), 1, _fp))
        return false;

    uint32_t len = ntohl(n);

    data.resize(len);
    if (len != fread(&data[0], 1, len, _fp))
        return false;

    return true;
    }

    bool write(uint32_t type, vector<uint8_t>& data) {
    uint32_t n = htonl(type);
    if (1 != fwrite(&n, sizeof(n), 1, _fp))
        return false;
    
    uint32_t len = data.size();
    n = htonl(len);

    if (1 != fwrite(&n, sizeof(n), 1, _fp))
        return false;

    if (len != fwrite(&data[0], 1, len, _fp))
        return false;

    return true;
    }

    bool close() {
    if (0 == _fp) {
        return false;
    }
    return 0 == fclose(_fp) ? true : false;
    }

    /*
     * Get a 32 bit unsigned int from the data array.
     *
     * @param data array containing the value.
     * @param offset in data to start reading.
     * @param u32 value read from array.
     *
     * @return true on success
     */
    bool get32(vector<uint8_t>& data, uint32_t offset, uint32_t& u32) {

    if (data.size() < offset + sizeof(u32))
        return false;

    u32 = data[offset + 0];
    u32 <<= 8;
    u32 |= data[offset + 1];
    u32 <<= 8;
    u32 |= data[offset + 2];
    u32 <<= 8;
    u32 |= data[offset + 3];
    
    return true;
    }

    /*
     * Put a 32 bit unsigned int into the data array.
     *
     * @param data array into which to place the value.
     * @param offset in data to start writing.
     * @param u32 value to put into the array.
     *
     * @return true on success
     */
    bool put32(vector<uint8_t>& data, uint32_t offset, uint32_t u32) {

    if (data.size() < offset + sizeof(u32))
        return false;

    data[offset + 0] = (u32 >> 24) & 0xff;
    data[offset + 1] = (u32 >> 16) & 0xff;
    data[offset + 2] = (u32 >> 8) & 0xff;
    data[offset + 3] = u32 & 0xff;

    return true;
    }

 private:
    FILE *_fp;
};

#endif // __LIBXORP_TLV_HH__